Bad Air Days in Sioux County, Nebraska: 5 a Year
5 bad air days a year
More bad air days than three quarters of monitored counties. Ranked 194 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% particle days).
The bad-air season here
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in July and August. Averaged over 2016 to 2025.
What actually helps here
- Ozone drives many bad days here. Purifiers and filters do not remove ozone, so do not buy one for that. Ozone peaks on hot afternoons: exercise outside in the morning.
The record for Sioux
The worst recent year was 2024, with 8 bad days on 319 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2024-07-24 | 143 | Ozone |
| 2024-07-25 | 143 | Ozone |
| 2024-07-23 | 136 | Ozone |
| 2024-07-26 | 122 | Ozone |
| 2024-07-27 | 122 | Ozone |
The air on a normal day
Across 533 monitored days from 2024 to 2025, the air in Sioux County rated Good on 83% of them, more often than the 72% typical of monitored counties, and Moderate on 16%. The median day sat at AQI 43; one day in ten went above 63.
The pollutant setting the AQI on an ordinary day here:
- ozone100%533 days
Sioux County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 214 | 187 | 27 | 0 | 0 | 42 | 100 |
| 2024 | 319 | 254 | 57 | 8 | 0 | 44 | 143 |
*2025 may be a partial year in EPA's file.
Elsewhere in Nebraska
- Douglas County4/yr
- Knox County3/yr
- Gage County1/yr
- Washington County1/yr
- Sarpy County1/yr
- Hall County1/yr
- Scotts Bluff Countyunder 1/yr
- Lancaster Countyunder 1/yr
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day, and on why a purifier does not touch ozone in smoke vs ozone.